Fast-Charging Cathodes from Polymer-Templated Mesoporous LiVPO4F.

Abstract

Fast-charging cathodes with high operating voltages are critical to the development of high energy and power density lithium-ion batteries. One route to fast-charging battery materials is through the formation of nanoporous networks, but these methods are often limited by the high calcination temperatures required for synthesis. Here, we report the synthesis of carbon-coated nanoporous LiVPO4F with excellent rate capabilities that can be stably cycled up to 4.6 V in standard LiPF6 electrolytes. During charge and discharge at 30C, 110 mAh/g (70% of theoretical capacity) was obtained, and only 9% of capacity was lost after 2000 cycles at 20C. These materials also showed excellent stability, with little self-discharge, an open-circuit voltage of 4.2 V, and a discharge capacity of 139 mAh/g obtained after holding for 12 h. Rate capabilities were further demonstrated in a proof-of-concept full cell made with a nanostructured Nb2O5. These devices were able to deliver 200 mAh/g at 1C and 100 mAh/g at 30C. Finally, operando X-ray diffraction and electrochemical kinetics were further used to provide insight into the nature of fast charging in these materials.